You are correct about adding back yield. That would make BND today worth about 80.50 in March 2021 dollars a bit less in January 2021 dollars.
It is still a dog that lost money in last 12 months since 12 months ago it was worth about 87 bucks. This is no surprise since bonds usually don't perform well in high inflation, very low rates and future rising rates environment.
Are we discussing bond performance after Ray Dalio's video? You keep bringing up bond performance before his video - predicting the past is not interesting. I predict high growth, high P/E stocks will do badly last month - I'm right! That's what you're applying here, when you talk about bond performance which Ray Dalio already saw when he made the video. It's not relevant to his prediction.
I rarely see anyone factor inflation into performance. I suspect if I went through your past posts, I would almost never see it factored into performance. It looks like you're trying to be right about bonds using inflation. After Ray Dalio's Mar 27 prediction, bonds went up for a few months. As of now, they are up very slightly from their start when you include interest in their total return. That is not "a dog", which I usually see ascribed to poor performance over many years.
People who bought 10% treasury bonds in the 1980s did extremely well, so high interest rates by themselves are not the problem. Repeated rate inflict losses on bonds equal to their duration, although the loss isn't uniform across all durations. The last point that bond rates are low, in my opinion, was caused by a Fed mistake.
Early in 2021, the Fed called inflation transitory. Chair Powell only admitted that as a mistake in November, after it was clear to everyone the Fed was wrong. The Fed predicted 2 rate hikes in 2022 back then, which has gone up every month to the current 2 rate hikes. The Fed is playing catch up.
